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Vaccine mismatch blamed in virulent flu season

Jason Cato
| Friday, Feb. 22, 2013, 1:21 a.m.

The nearly 7,000 confirmed cases of the flu this season in Western Pennsylvania help validate new information from state and federal health agencies: More people are getting sick from influenza, including nearly half of those who got a flu shot.

“There seems to be a mismatch in the vaccine and the strains we're seeing,” said Dr. Marc Itsko-witz, an internal medicine specialist at Allegheny General Hospital in Pittsburgh.

The Centers for Disease Control and Prevention on Thursday reported the flu vaccine is 56 percent effective — which is considered moderately successful. The agency amended an earlier estimate that the vaccine appeared to be 62 percent effective.

Scientists consider a 60 percent to 70 percent effectiveness rate for a flu vaccine to be good, as flu viruses mutate quickly and multiple strains can circulate at once.

The CDC estimate is based on information from almost 2,700 children and adults enrolled in the federal Influenza Vaccine Effectiveness Network's five study sites — one of which is the University of Pittsburgh Schools of the Health Sciences in partnership with UPMC.

The CDC estimate shows that the vaccine is 27 percent effective in adults 65 and older nationwide, but only 9 percent effective in preventing illness from Influenza A — the most common and deadliest strain — in that age group.

Those estimates are based on 300 people in the study, which is too small a sample to draw solid conclusions, said Dr. David Nace, chief medical officer for UPMC Senior Communities.

“I think the vaccine overall this year was pretty good,” Nace said. “We saw a lot of flu. But I think this would have been a heck of a lot worse without it.”

Extreme incidence waning

More than 34,000 people across Pennsylvania have tested positive for the flu this season, according to the state health department.

That is nearly 12,000 more than during the last two years combined.

“This was the earliest and busiest flu season in the last 10 years,” Itskowitz said. “Last year was the lowest and shortest peak ever.”

In 2011-12, there were only 3,020 reported cases statewide. Of those, 542 cases came from the Alle-Kiski Valley's four counties.

This flu season, 4,774 reported flu cases have come from the A-K Valley.

The number of cases is declining each week, according to Pennsylvania Health Department spokeswoman Kate Gillis.

“We've seen a significant dropoff, but the numbers are still relatively high,” Gillis said.

There were 1,082 cases reported last week, down from 1,876 cases the week before.

According to Gillis, 14 people across the state died last week from complications related to the flu, none of them from Western Pennsylvania.

That brings the state's flu-related death total to 154, the most since flu-season records were first kept in 2003, including 14 from Allegheny County. Those local victims ranged in age from 53 to 98, according to Allegheny County Health Department spokesman Guillermo Cole.

Flu-like illnesses account for about 3 percent of emergency room visits, down from a peak of 7 percent weeks ago. Flu accounts for 2 percent of hospital visits all year.

Gillis said there are things people can do to prevent the spread of the flu, even though it's fading away. “It's very important to wash your hands with soap and water,” she said. “Also, wiping things down with disinfectant is always a good idea.

“And, it's never too late to get a flu shot, you might still need it.”

Looking ahead

Nearly all the flu cases in Allegheny County this season involved Influenza A, Cole said, though hospitals now are reporting a spike of Influenza B.

Starting next year for the first time, manufacturers will produce a flu vaccine that contains four strains — two each for Influenza A and Influenza B — instead of three.

Researchers at Pitt are working on more effective flu vaccines, said Dr. Ronald Montelaro, co-director of the school's Center for Vaccine Research. Those vaccines would focus on parts of the flu virus that do not change rather than proteins, which often morph and dupe the immune system into attacking the wrong part of the virus, he said.

“This virus continues to evolve. It's a moving target,” Montelaro said. He predicts that more effective vaccines would be available within a decade.

But people shouldn't skip the ones available now, he said, even if it works for just over half of those who take it.

Nearly 135 million doses of this season's flu vaccine had been distributed through Feb. 15, CDC records show.

Montelaro noted that many who got the flu after being vaccinated experienced milder symptoms and a shorter illness.

“And that's not a bad outcome for people who the vaccine didn't protect completely,” he said.

Jason Cato is a staff writer for Trib Total Media. Trib Total Media freelance writer R.A. Monti contributed to this report.

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